In the conventional private part cleaning device using the instant heating technology, water is heated to a specified temperature instantly by using a heating apparatus which can heat the water quickly. To ensure a temperature of the heated water to be uniform, the heating apparatus is usually provided with a buffer water tank in communication with a heating cavity. The buffer water tank is usually in communication with the heating cavity via a narrow water path, in this way, the heated water flows out after being mixed with the water in the buffer water tank in some extent. The heating apparatus has the following disadvantages.
On one hand, there is no good heat exchange between the heating cavity and the buffer water tank. When the water temperature rises suddenly, in order to cause the temperature of the superheated water after being mixed by the buffer water tank to be close to a normal temperature and avoid the superheated water from spraying to a private part of a human body, it is generally required to mix a large volume of a normal-temperature water with the superheated water. In this case, a volume of the buffer water tank is large, therefore an overall volume of the heating apparatus is large and further miniaturization of the heating apparatus cannot be realized. Moreover, since the water temperature is always higher than the normal temperature after the superheated water is mixed with the normal-temperature water in the buffer water tank, the user may feel uncomfortable. The heating apparatus cannot ensure the stability of an outlet water temperature reliably.
On the other hand, when special situations occur, such as water supply cutoff, the temperature of the water in the heating cavity rises sharply. Since the buffer water tank is in communication with the heating cavity via a narrow water path, there is no good heat exchange between the buffer water tank and the heating cavity. Hence, the temperature of the water in the buffer water tank rises slowly. A temperature detector arranged in the buffer water tank cannot know the situation and a controller cannot cut off the power supply in a timely manner to ensure safety. For this reason, it is required to add devices, such as a flowmeter, to detect the abnormal situations, which results in that the heating apparatus has more components and a high cost.